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During directional solidification, segregation of alloying components may lead to channels of segregate forming, called ‘freckle’. This work aims to understand how the application of a magnetic field effects freckle formation. Using synchrotron X-ray imaging we quantify the influence of magnetic field strength and orientation on the formation, growth and motion of freckle channels and the resulting suppression of the solidification temperature.By increasing the Bz magnetic component (perpendicular to the sample surface, freckle channels can be driven to one side and suppressed elsewhere, giving a freckle free region in otherwise difficult to cast alloys. The freckle motion can be attributed to the thermoelectric Lorentz force acting on the liquid, changing inter-dendritic liquid flow by causing the solute-enriched liquid to accumulate at one side, biasing channel motion. In the bulk liquid electromagnetic damping force prevails, decreasing the solidification temperature.

The formation of freckle defects in the presence of a static magnetic field is studied by combining in-situ synchrotron imaging with numerical simulations. The formation, growth and motion of freckle channels during directional solidification are investigated in a Hele-Shaw cell for a low melting point Ga-In alloy. The solidification setup is developed at HZDR and is described in detail elsewhere. The solidification cell is placed in a permanent magnet system providing a flux density of about 120 mT within the cell. The turn of the magnet system about a vertical cell axis allow to get both the Bx (perpendicular to a X-ray beam) and the Bz (parallel to a X-ray beam) component of the magnetic field. Numerical simulations, using a microscopic parallelized Cellular Automata lattice Boltzmann method, are validated by these in situ experiments. An excellent match between the numerical model and experiments conducted on thin rectangle sample alloy is achieved. Evaluation of the in situ X-ray data and numerical analysis shows the role of thermoelectric magnetohydrodynamics (TEMHD) and electromagnetic damping (EMD) in the formation of channels and ultimately freckle defects. For instance, Figures 1c and 1d show clear evidence of the effect of the magnetic field on the microstructure. Figure 1d displays the formation of a solute channel at the left side of the sample in the presence of a magnetic field. This channel development can be attributed to the thermoelectric Lorentz force acting on the inter-dendritic liquid flow by causing the solute to accumulate at one side of the cell. In situ synchrotron experiments allow us to resolve the complex channel dynamics and simultaneously show how large-scale flow fields may alter them. Both temperature gradient and grain orientation can affect the dynamics of the segregation channels formation in the presence of the magnetic field. The effect of electromagnetic damping force to convective transport needs future investigations. The in situ synchrotron data and numerical modelling will provide further understanding of the underlying mechanisms and identifying further interesting phenomena.

The formation of freckle defects in the presence of an external magnetic field is studied by combining *in situ* synchrotron imaging with numerical simulations. The formation, growth and motion of freckle channels during directional solidification are investigated in a Hele-Shaw cell for a low melting point Ga-In alloy. The solidification cell is placed in a permanent magnet system providing a flux density of about 120 mT within the cell. A parallel numerical study, using a microscopic parallelized Cellular Automata lattice Boltzmann method, is validated by these *in situ* experiments. An excellent match between the numerical model and experiments conducted on thin rectangle sample alloy is achieved. Evaluation of the *in situ* X-ray data and numerical analysis shows the role of thermoelectric magnetohydrodynamics (TEMHD) and electromagnetic damping (EMD) in the formation of channels and ultimately freckle defects. The channel motion can be attributed to the thermoelectric Lorentz force acting on the inter-dendritic liquid flow by causing the solute to accumulate at one side of the cell. *In situ* synchrotron experiments allow us to resolve the complex channel dynamics and simultaneously show how large-scale flow fields may alter it. Both temperature gradient and grain orientation can affect the dynamics of the segregation channels formation in the presence of the magnetic field. The effect of electromagnetic damping force to convective transport needs future investigations. The *in situ* synchrotron data and numerical modelling will provide further understanding of the underlying mechanisms and identifying further interesting phenomena.

Osteoporosis is characterised by trabecular bone loss resulting from increased osteoclast activation and unbalanced coupling between resorption and formation, which induces a thinning of trabeculae and trabecular perfo rations. Bisphosphonates are the frontline therapy for osteoporosis, which act by reducing bone remodelling, and are thought to prevent perforations and maintain microstructure . However, bisphosphonates may oversuppress remodelling resulting in accumulation of microcracks. This paper aims to investigate the effect of bisphosphonate treatment on microstruc ture and mechanical strength. Assessment of microdamage within the trabecular bone core was performed using synchrotron X-ray micro- CT linked to image analysis software. Bone from bisphosphonate-treated fracture patients exhibited fewer perforations but more numerous and larger microcracks than both fracture and non-fracture controls. Furthermore, bis phosphonate-treated bone demonstrated reduced tensile strength and Young’s Modulus. These fi ndings suggest that bisphosphonate therapy is effective at reducing perforations but may also cause microcrack accumulation, leading to a loss of microstructural integrity and consequently, reduced mechanical strength.

Energy-dispersive X-ray diffraction was used to follow the reduction of UO2 to U in LiCl–KCl eutectic. A novel electrochemical cell was designed and constructed in order to follow molten-salt electrochemical investigations in situ., A novel electrochemical cell has been designed and built to allow for in situ energy-dispersive X-ray diffraction measurements to be made during reduction of UO2 to U metal in LiCl–KCl at 500°C. The electrochemical cell contains a recessed well at the bottom of the cell into which the working electrode sits, reducing the beam path for the X-rays through the molten-salt and maximizing the signal-to-noise ratio from the sample. Lithium metal was electrodeposited onto the UO2 working electrode by exposing the working electrode to more negative potentials than the Li deposition potential of the LiCl–KCl eutectic electrolyte. The Li metal acts as a reducing agent for the chemical reduction of UO2 to U, which appears to proceed to completion. All phases were fitted using Le Bail refinement. The cell is expected to be widely applicable to many studies involving molten-salt systems.

Objectives: Bisphosphonates (BP) are the first-line treatment for preventing fragility fractures. However, concern regarding their efficacy is growing because bisphosphonate is associated with over-suppression of remodelling and accumulation of microcracks. While dual-energy X-ray absorptiometry (DXA) scanning may show a gain in bone density, the impact of this class of drug on mechanical properties remains unclear. We therefore sought to quantify the mechanical strength of bone treated with BP (oral alendronate), and correlate data with the microarchitecture and density of microcracks in comparison with untreated controls.Methods: Trabecular bone from hip fracture patients treated with BP (n = 10) was compared with naïve fractured (n = 14) and non-fractured controls (n = 6). Trabecular cores were synchrotron scanned and micro-CT scanned for microstructural analysis, including quantification of bone volume fraction, microarchitecture and microcracks. The specimens were then mechanically tested in compression.Results: BP bone was 28% lower in strength than untreated hip fracture bone, and 48% lower in strength than non-fractured control bone (4.6 MPa vs 6.4 MPa vs 8.9 MPa). BP-treated bone had 24% more microcracks than naïve fractured bone and 51% more than non-fractured control (8.12/cm2vs 6.55/cm2vs 5.25/cm2). BP and naïve fracture bone exhibited similar trabecular microarchitecture, with significantly lower bone volume fraction and connectivity than non-fractured controls.Conclusion: BP therapy had no detectable mechanical benefit in the specimens examined. Instead, its use was associated with substantially reduced bone strength. This low strength may be due to the greater accumulation of microcracks and a lack of any discernible improvement in bone volume or microarchitecture. This preliminary study suggests that the clinical impact of BP-induced microcrack accumulation may be significant.

Preservice elementary teachers, enrolled in an inquiry oriented science and social science methods course, were given pre- and posttests concerning their preferences for memorized facts (M), applications(A), or questioning (Q) in true statements related to subjects studied; scores on M and A changed as predicted. The questionnaire is included. (SD)

To investigate the fracture behaviour of polygranular graphite (a quasi-brittle material), crack propagation in a short bar chevron notched specimen was studied by synchrotron X-ray computed tomography combined with digital volume correlation. Displacements were measured within the loaded test specimen, particularly the three-dimensional (3-D) profile of crack opening displacement. Analysis of the 3-D displacement field confirmed the existence of distributed damage in a fracture process zone, which significantly increased the effective crack length. Finite element simulations affirmed that the measured crack opening profiles could be reproduced using a cohesive zone model, but not with a linear elastic analysis. Comparing the simulation to the experimental results, it was deduced that the critical strain energy release rate varied across the crack front, i.e. the fracture toughness is constraint-dependent. This is proposed to be a general characteristic of quasi-brittle materials. Copyright 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Solidification morphology directly impacts the mechanical properties of materials; hence many models of the morphological evolution of dendritic structures have been formulated. However, there is a paucity of validation data for directional solidification models, especially the direct observations of metallic alloys, both for cellular and dendritic structures. In this study, we performed 4D synchrotron X-ray tomographic imaging (three spatial directions plus time), to study the transition from cellular to a columnar dendritic morphology and the subsequent growth of columnar dendrite in a temperature gradient stage. The cellular morphology was found to be highly complex, with frequent lateral bridging. Protrusions growing out of the cellular front with the onset of morphological instabilities were captured, together with the subsequent development of these protrusions into established dendrites. Other mechanisms affecting the solidification microstructure, including dendrite fragmentation/pinch-off were also captured and the quantitative results were compared to proposed mechanisms. The results demonstrate that 4D imaging can provide new data to both inform and validate solidification models.

A variable volume flow cell has been integrated with state-of-the-art ultra-high speed synchrotron x-ray tomography imaging. The combination allows the first real time (sub-second) capture of dynamic pore (micron) scale fluid transport processes in 4D (3D + time). With 3D data volumes acquired at up to 20 Hz, we perform in situ experiments that capture high frequency pore-scale dynamics in 5–25 mm diameter samples with voxel (3D equivalent of a pixel) resolution of 2.5 to 3.8 µm. The data are free from motion artefacts, can be spatially registered or collected in the same orientation making them suitable for detailed quantitative analysis of the dynamic fluid distribution pathways and processes. The method presented here are capable of capturing a wide range of high frequency non equilibrium pore-scale processed including wetting, dilution, mixing and reaction phenomena, without sacrificing significant spatial resolution. As well as fast streaming (continuous acquisition) at 20 Hz, it also allows larger-scale and longer term experimental runs to be sampled intermittently at lower frequency (time-lapse imaging); benefiting from fast image acquisition rates to prevent motion blur in highly dynamic systems. This marks a major technical breakthrough for quantification of high frequency pore scale processes: processes that are critical for developing and validating more accurate multiscale flow models through spatially and temporally heterogeneous pore networks.

Better understanding of the distribution of elastic and plastic strains in deformed polycrystalline, multiphase materials is important for structural engineering. The deformation response depends upon the interaction of grains of different orientations, and the anisotropy associated with each phase. Strain partitioning and tensile-compressive hardening asymmetry arises due to mismatches in modulus and ductility between grains and phases in alloys such as Ti-6Al-4V that displays both strong anisotropy within one phase and significant differences of properties between phases. Simple four-point bent beam samples were studied using the newly available energy-dispersive X-ray diffraction setup at the high energy white-beam synchrotron beamline I12 (JEEP) at Diamond Light Source. Diffraction patterns from the bent polycrystalline Ti6Al4V samples were collected using the new 23-cell "horseshoe" detector and interpreted using Pawley refinement to extract unit cell parameters, thus allowing elastic strain to be determined. The tensile-compressive hardening asymmetry was quantified for the grains oriented with the basal plane perpendicular to the loading direction. Initial evaluation of the performance of the new instrument is reported. © 2011 Elsevier Ltd. All rights reserved.